The present invention is directed to the art of fiber optics, specifically to the use of optically transmissive bodies as illuminating devices.
Fiber optics, including both filament and other shaped bodies have found use in many applications, for instance, as ornamental lighting, display lighting and in the transmission of information.
One particular application for which fiber optics have been used is as illuminators. An illuminator is a device where the light, which is normally traversing longitudinally through the optically transmissive body, is diverted laterally outward from the body at various points to illuminate given areas.
Illuminators are formed by modifying a optically transmissive body to "leak" an incremental amount of the total amount of light passing therethrough laterally outward. Thus by using only a single light source, i.e., a bulb, numercus areas may be lighted using one or more illuminators prepared in this manner. Since the illumination of these multiple areas would normally require more than bulb, the efficiency of the overall lighting system in greatly increased by the use of an optical illuminator.
There are numerous methods by which an fiber optic can be prepared to effect a lateral transmission of light. For example, the fiber optic body can be cut with grooves at various points along its length, with one or more of the groove surfaces coated with a reflective material. This reflective material will reflect any light which impinges upon it. By properly positioning the grooved surfaces light can be directed in any desired direction.
An angular mirror arrangement imbedded in or laid along the fiber optic body can be substituted for the mirror coated groove surfaces. Fiber optic bodies modified in this manner will transmit light in a similar manner as the light impinges upon the mirrored surfaces.
Examples of optical illuminators prepared by the discussed techniques are generally disclosed in U.S. Pat. Nos. 4,052,120 issued to Sick et al.; 4,173,390 issued to Kach; and 4,196,962 issued to Sick.
Another example of an optical illuminator is where a fiber optic is coated along a portion of its peripheral surface with an illuminant material. This illuminant surface functions as a secondary light source reflecting light generally inward and toward the opposite side of the body, if such side is not coated out therethrough. A fiber optic illuminator prepared by this technique is disclosed in U.S. Pat. No. 4,128,332 issued to Rowe.
Another technique of modifying a fiber optic body to prepare an illuminating device involves roughing a portion of the peripheral surface of the fiber optic body. The light will pass out through this roughened surface. A fiber optic prepared in this manner is disclosed in U.S. Pat. No. 3,829,675.
Fiber optics have also be prepared, as disclosed in U.S. Pat. No. 4,172,631 issued to Yevick, to possess spaced apart longitudinal reflecting surfaces. The fibers are compatibly grooved and laid on a reflective material. The finished product thus includes a multiplicity of mirrored surfaces positioned along the length of the fibers. The height or depth of these surfaces are specifically calculated to provide for the reflection radially inward of an incrementally increasing quantity of the total light passing through the fiber. This light will pass across and through the opposite side of the fiber.
While optical illuminators prepared by the discussed techniques provide some lateral light emission, the degree of light emitted is not always adequate, and the methods of preparing these optical illuminating devices is generally costly. That is, the imbedding of mirror assemblies into a fiber optic or the coating of grooved surfaces is costly. There thus exists a need for a technique by which optical illuminators can be easily prepared in an economical manner. There also exists a need for an optical illuminator which provides greater illumination.